Support for fonts currently depends on the type of vidconsole in use. Add
two new methods to enumerate fonts and to set the font.
Fix a few other method comments while we are here.
Signed-off-by: Simon Glass <sjg@chromium.org>
Add a new 'font' command which allows the fonts to be listed as well as
selecting a different font and size.
Allow the test to run on sandbox, where multiple font/size combinations
are supported, as well as sandbox_flattree, where they are not.
Signed-off-by: Simon Glass <sjg@chromium.org>